Novel HDGF/HIF-1α/VEGF axis in oral cancer impacts disease prognosis

BackgroundHepatoma-derived growth factor (HDGF) participates in angiogenesis and represents a negative prognostic factor in oral cancer. The current study was designed to elucidate the regulatory mechanism between HDGF and vascular endothelial growth factor (VEGF) and the clinical impact of oral cancer.MethodsTCGA data and surgical samples from oral cancer patients were used for the clinicopathological parameter and survival analysis. Human oral cancer SCC4 and SAS cells were treated with recombinant HDGF protein. VEGF gene expression and protein level were analyzed by RT-PCR, Western blotting, and enzyme-linked immunosorbent assay. The signaling pathways for regulating VEGF expression were investigated. The nucleolin neutralizing antibody and HIF-1 alpha inhibitor were applied to SCC4 cells to investigate their effects on the HDGF-stimulated VEGF pathways.ResultsTCGA and immunohistochemical analysis revealed a positive correlation between HDGF and VEGF expression in oral cancer tissues. Recombinant HDGF significantly increased VEGF gene and protein expression in oral cancer SCC4 cells in a dose-dependent manner. HDGF enhanced the phosphorylation levels of AKT and IkB and the protein level of HIF-1 alpha and NF-kappa B. The nucleolin-neutralizing antibody abolished HDGF-stimulated HIF-1 alpha, NF-kappa B and VEGF protein expression in SCC4 cells. The HIF-1 alpha inhibitor antagonized the HDGF-induced VEGF gene expression. High VEGF expression was strongly correlated with HDGF expression, advanced disease, and poor survival.ConclusionThis study postulated a new pathway in which HDGF activated HIF-1 alpha and then induced VEGF expression through binding to membrane nucleolin under normoxic conditions, leading to poor disease control. The HDGF/HIF-1 alpha/VEGF axis is important for developing future therapeutic strategies.